Histomorphometric Analysis of Sun-exposed and Nonsun-exposed Sites of Skin among North Indian Female Population

Abstract Background: Knowing the normal values of different layers of skin is important, especially for esthetic and plastic surgeons in skin transfer operations, skin-related disorders, and their clinical investigations in drugs and vaccine research. Effects of ultraviolet (UV) rays are seen in the form of pigmentation, age spots, tanning, freckles, crow’s feet, etc. These features are less observed in sun-protected areas. This study aims to compare the measurement of skin layers under the following parameters: stratum corneum, epidermis (Epd), papillary dermis, reticular dermis (Rd), and total dermis, in sun-exposed (SE) and nonsun-exposed (NSE) skin. Methodology: Twenty tissue samples of human skin, each from the forehead (SE) and lower part of the abdomen (NSE) from female deceased bodies, were taken. After tissue processing and staining with hematoxylin and eosin stains, slides were analyzed histometrically. Results: The median thickness of stratum corneum, Epd, and Rd was higher in the SE area when compared to the NSE area of female skin with significant P values of 0.036, 0.026, and 0.002, respectively. Conclusions: These parameters are influenced by factors such as environment and lifestyle, out of which a major role is played by UV rays. Histometric studies can be useful in selecting the formulation of proper active ingredients according to the thickness which can be attuned in better treatment and cosmetic outcomes as the thickness of stratum corneum is a rate-limiting factor in dermatopharmacokinetics.